In the manufacture of containers such as glass or plastic bottles and jars, the container typically is formed with a finish having an axis and means for securing a closure to the finish. The finish has an open mouth surrounded by an axially facing sealing surface for sealing engagement with a closure applied to the container. Manufacturing anomalies can occur at the container sealing surface, such as a warp, a dip or an off-level condition, also known as a cocked sealing surface. A “warp” at the sealing surface generally refers to departure of the sealing surface from a planar configuration. A “dip” at the sealing surface refers to an unfilled area at the sealing surface, typically narrower and deeper than a warp. “Off-level” refers to a tilt of the average plane of the sealing surface from an orientation perpendicular to the finish axis. Warp, dip and off-level anomalies at the sealing surface can occur in combinations, and can affect the ability of an automatic capping machine to apply a closure to the finish and/or to the ability of the closure to form an effective seal against the sealing surface. Other variations in sealing surface level include over-height and under-height at the sealing surface, which refer to departure of the sealing surface from a nominal height for the container under inspection.
U.S. Pat. No. 5,489,987, assigned to the assignee of the present application, discloses an apparatus and method for inspecting the sealing surface of a container, which includes a light source positioned to direct a narrow beam of light energy at an acute angle onto the sealing surface of a container. A light sensor is disposed to receive the narrow beam of light energy reflected from the sealing surface, and provides an output that varies as a function of the position of incidence of the reflected beam on the sensor. The sensor is coupled to associated electronics for providing information indicative of container height and a signal for controlling separation of the container from a conveyor system when the height of the container, the warp or dip at the container sealing surface, or an off-level condition at the sealing surface exceeds predetermined standards. In one embodiment, a light source/sensor pair is provided at diametrically opposed sides of the container finish. Dips at the sealing surface and an off-level container finish are identified and measured as a function of a difference between the sensor output signals, while a warped sealing surface is identified and measured as a function of a sum of the sensor output signals. Height of the container and variations in height between successive containers may be determined as a function of the output signal from either or both of the sensors. U.S. Pat. Nos. 5,896,195 and 6,025,909, also assigned to the assignee of the present application, disclose a container sealing surface inspection apparatus and method in which the narrow beam from the light source is line-shaped, having an elongated dimension chordally of the container finish for accommodating wobble at the container finish.
The present invention embodies a number of aspects that may be implemented separately from or more preferably in combination with each other.
Apparatus for inspecting a container finish in accordance with a first aspect of the present invention includes at least one light source for directing light energy onto the sealing surface of a container. At least one light sensor is disposed to receive light energy reflected from the sealing surface of the container, and is responsive to such reflected light energy to provide signals indicative of the level of the scaling surface at at least four predetermined points on the sealing surface spaced from each other around the axis of the container finish. An information processor is responsive to such signals for detecting variations in level at the sealing surface of the container. In the preferred embodiments in accordance with this aspect of the invention, the predetermined points on the sealing surface from which reflected energy is received at the sensor are at a nominal angle of 90° from each other. The information processor preferably is responsive to such signals for detecting warp, dip, off-level and overall height variations at the sealing surface. In the preferred embodiments, the container is moved (e.g., rotated or moved laterally) so that the spaced inspection points effectively sweep the sealing surface. A less preferred alternative would be for the inspection apparatus to move while the container is stationary so that the at least one sensor sweeps the container sealing surface. The motions could be combined, so that a rotating inspection apparatus moves laterally, for example, to follow a laterally moving container.
Apparatus for inspecting the sealing surface of a container finish in accordance with another aspect of the invention includes a first light source for directing light energy onto a first point on the sealing surface of the container, and a first light sensor for receiving light energy reflected from the first point on the sealing surface to provide a signal indicative of level at the first point. A second light source directs light energy onto a second point on the sealing surface circumferentially spaced from the first point around the axis of the container finish, and a second light sensor receives light energy reflected from the second point to provide a signal indicative of level at the second point. An information processor is responsive to the signals for detecting variations in level at the first and second points on the sealing surface. The first light source/sensor pair and the second light source/sensor pair are simultaneously adjustable with respect to the axis of the container finish to accommodate inspection of container finishes of differing diameters. In the preferred embodiments of this aspect of the invention having four light source/sensor pairs responsive to circumferentially spaced points on the container sealing surface, each light source/sensor pair is each provided in the form of a subassembled probe. The probes are disposed in opposed pairs that are simultaneously adjustable radially inwardly and outwardly with respect to the finish axis. In the preferred embodiment, one pair of probes is directly coupled to a threaded rod, and the other pair of probes is coupled to the rod through a cam plate and a cam shaft, so that rotation of the threaded rod simultaneously and equally adjusts all four probes with respect to the container axis.
Apparatus for inspecting the sealing surface of a container finish in accordance with a third aspect of the invention includes a first light source for directing light energy onto a first point on the sealing surface of the container, and a first light sensor for receiving light energy from the first source reflected from the first point to provide a first signal indicative of level at the first point on the sealing surface. A second light source directs light energy onto a second point on the sealing surface circumferentially spaced 90° from the first point around the axis of the container finish, and a second light sensor receives light energy from the second source reflected from the second point to provide a second signal indicative of level at the second point on the sealing surface. The container is rotated such that the finish and the sealing surface rotate about the axis of the finish. An information processor periodically scans the first and second sensors to provide a periodic signal that varies as a function of the first and second signals. The information processor is adapted to separate this periodic signal into first and second components, having respective periods of 180° and 360° of finish rotation, to determine off-level at the sealing surface as a function of the 360° component and to determine warp at the sealing surface as a function of the 180° component.